A game apparatus is known regarding which odds (a magnification as to in what multiples game media, such as bet medals, return as a winning allotment) are set for each of a plurality of betting targets, as in a dice game, etc. (see Patent Documents 1, 2, etc.). Patent Document 1 discloses that odds ranging from 1:1 to 180:1 are set for each of a plurality of betting targets according to the appearance probability of a betting target.
In the above-described game apparatus, the total number of game media paid back via allotment with respect to the total number of game media bet by a player is controlled as a payout (PO) ratio. An installer for game apparatuses specifies a payout ratio (set payout ratio) for each game apparatus or for each business, and sets the odds, etc., such that an actual payout ratio approaches a set payout ratio.